Toronto: S. Williams d. Radwanska

It’s hard to imagine two top players whose styles contrast more than Serena Williams' and Agnieszka Radwanska's. It’s almost as if the world No. 1 and No. 4 play different sports—one is all-powerful, the other all-finesse. Which can make their match-ups a little strange; points between them can be interesting and ugly at the same time.

There was plenty of both—interest and ugliness—in Williams’ 7-6 (3), 6-4 win in their Toronto semi on Saturday night. Points and games were often long and complicated, with Serena dictating and Radwanska scrambling. Between Aga’s drops and lobs, both women found themselves running to all four corners of the court, sometimes in the same rally. But as expected, most of those rallies were decided on Serena’s racquet. As she went, so went the quality of the match, and that quality was decidedly up and down. On the up side, Serena finished with 43 winners and was 25 of 30 at the net; on the down, she committed 47 errors and made just 54 percent of her first serves.

Serena wasn’t feeling well, physically or mentally. For the most part, she was tense, uptight, and pressing; she may have set the record for the most number of sighs and eye-rolls in a winning effort. But it wasn’t just her game that was off; her body was as well. Serena took some pills at the end of the first set, and by the end of the second, as the points became more demanding, she looked like she might hyperventilate. But she never lost control of the match, and she dug in when it mattered. Serena attacked her way to a 7-3 win in the first set tiebreaker, broke back with a smash and a holler at 2-3 in the second, and gritted her teeth through a critical 10-minute game to hold at 4-4 later in that set.

For Radwanska, who had lost her last two matches to Serena 6-2, 6-1, and 6-0, 6-3, this must count as progress. She hit 34 fewer winners than Williams, and her second serve sat up begging to be smacked. But she made Serena work and fret, and she came up with her share of strong first serves herself. It goes without saying that Aga also threw in more than a few no-look reflex winners, perfect defensive lobs, and ghost-in volleys that wrong-footed her opponent.

But finesse finally fell to power. In the last game, Radwanska double faulted at 15-15. Serena, sensing her chance, pounced with two quick winners—this long and involved contest was over with stunning speed. On Sunday, Serena will try to win her eighth title of 2013, against Sorana Cirstea.